Geant4 Simulations for the Radon Electric Dipole Moment Search at

energies, branching ratios, emission times and angular distributions from calculated
probability distributions. Random numbers were generated from a uniform distribution
between [0.0, 1.0) to select from these probability distributions. The random
numbers were generated with the srand48 anddrand48 functions fromthe C++ standard
library, where the srand48 function was seeded on the system clock to ensure
initial randomness during each use.
3.2.1 Geant4
Geant4isaC++toolkitusedtosimulatethepassageofparticlesthroughmatter
[37]. Encompassing an abundant set of physical models, Geant4 handles geometry,
physical processes andparticle interactions. Geant, which isusually pronounced like
the French word géant (giant), stands for “GEometry ANd Tracking”. The Geant
code was originally developed by CERN for high-energy physics simulations. Today
Geant4 is the leading computation method for high-energy, nuclear and accelerator
physics simulations, as well as a growing influence in the medical and space science
fields.
Geant4 simulations are built upon well-developed Monte Carlo models which
are tested and maintained by the Geant4 collaboration of scientists and software
engineers [38]. Geant4 users construct three-dimensional simulation environments
by defining volumes and materials. From simple geometrical shapes, such as cubes,
spheres, cylindersandcones, complexgeometriesarebuilt, wherethematerialsaredefined
by combinations of atomic elements. Inside the three-dimensional environment,
usersfireparticles(α,β,γ,neutron, proton,etc.) withdefinedenergiesanddirections.
Interactions which deposit energy in defined materials lead to the recording of energy,
time, and position information. Interactions that lead to the cascading production of
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